1. Field of the Invention
The invention concerns a method for the simultaneous preconcentration and preselection of at least one group of used polymer materials of various compositions, in a mix with each other and with contaminating materials, coming from the destruction by grinding of durable consumer goods that have arrived at the end of their life, able to be recycled in the fields of plastics technology.
2. Description of Related Art
An important problem is posed in the industries for recycling used polymer materials coming from the destruction by grinding of durable consumer goods at the end of their life, which is:                the low concentration of these upgradable used polymer materials in the flow of materials to be treated coming from the destructive grinding, where it is desirable to improve this concentration to make reprocessing thereof maximum,        and their great diversity in nature and composition such as for example polyolefins, polyamides, polyvinyl chlorides and others, with or without fillers.        
Industrial waste sorting equipment is technically specialised and suitable for the treatment of one particular type of waste such as for example upgradable used polymers, to be extracted from the grinding residues of durable consumer goods at end of their life, such as motor cars and domestic electrical equipment of other origins from which the metals have already been extracted in the main but which, in this other step, must be separated from contaminating materials in large quantities. This is why waste sorting equipment can be effective only provided that it is supplied with a flow of waste suited to it.
Equipment for sorting industrial waste such as used polymer materials, coming from the destruction by grinding of durable consumer goods at the end of their life, is not always (directly) installed on the site for the destruction by grinding of said goods and it consequently appears economically necessary to as far as possible enrich, with upgradable used materials, the waste to be transported from the destruction site to the reprocessing site.
In order to improve the reprocessing of waste and to make it maximum, it is necessary to feed the sorting equipment that is specialised for one type of waste with flows to be treated that are already preconcentrated with materials to be reprocessed.
This type of preconcentration of waste consequently has at least two objectives including the following:                one is to separate the waste in order to orient it to the specialised processing means,        and the other is to preconcentrate a flow of waste to be treated loaded with upgradable materials in order to improve the overall efficiency of the waste processing chain by increasing the “mass of sorted products to be reprocessed compared with the total mass of products entering the waste processing chain” ratio.        
However, it appears in the exploitation of this waste that preconcentration alone is insufficient in itself and that it is necessary simultaneously, during this preconcentration operation, to effect a preselection by grouping of the used polymer materials to be reprocessed in order to create specific flows of upgradable used materials accompanied by contaminating materials, not only with a much greater concentration of upgradable used polymers but also specific to the types of used polymers preselected by grouping making it possible both to simplify the equipment for reprocessing each type of polymer and to make it more economical and to recover almost all the polymers present in said waste while even further preserving the environment through a drastic reduction in the waste dumped.